Method for the production of water-in-water polymer dispersions

ABSTRACT

The invention relates to methods for manufacturing a water-in-water polymer dispersion containing polymer A and at least one polymeric dispersant B, according to which monomers, which are dispersed in an aqueous phase containing water-soluble dispersant B, are subjected to radical polymerisation, possibly following the addition of a water-soluble salt, and, after polymerisation, a water-soluble acid is added to the water-soluble and/or water-swellable polymer A obtained in this way, where the acid is added in quantities of 0.1 to 0.5% by weight and the salt in quantities of up to a maximum of 3% by weight, each referred to the total dispersion, and the total quantity of salt and acid amounts to a maximum of 5% by weight, referred to the total dispersion.

[0001] The present invention relates to methods for manufacturingwater-in-water polymer dispersions containing a finely dispersed,water-soluble or water-swellable polymer A and a continuous, aqueousphase containing a polymeric dispersant B, the water-in-water polymerdispersions obtainable in this way and their use as auxiliaries inpapermaking or as flocculants in the sedimentation of solids.

[0002] The manufacture of water-in-water polymer dispersions isdescribed repeatedly in the prior art. The main target in this contextis to obtain water-in-water dispersions that are easier to handle. Thus,it is known from international application WO 98/14405 that the additionof a mixture of a cosmotropic and a chaotropic or an anionic, organicsalt during the manufacture of the dispersed polymer component iscapable of lowering the viscosity of the water-in-water dispersions.

[0003] International application WO 98/31748 describes water-in-waterdispersions which are stable and, despite a relatively high content ofdispersed polymers, pourable, provided that, during production of thewater-in-water dispersions, a water-soluble, inorganic salt is added tothe dispersed monomer solution in quantities of at least 10% by weightprior to polymerisation. High salt quantities of this kind are notacceptable for some applications of water-in-water dispersions.

[0004] International application WO 98/31749 describes water-in-waterdispersions which remain pourable and display no irreversibleagglomeration in storage, provided that the water-in-water dispersionsare already pourable after their production on account of their lowviscosity. According to the teaching of this international application,this is achieved in that a polyhydroxy compound is added to thedispersion medium in which the monomer solution to be polymerised ispresent. However, when being further diluted, the water-in-waterdispersions obtained, which may possibly also contain salts, must bediluted beyond a certain degree, because an undesirably great increasein the Brookfield viscosity otherwise occurs during dilution compared tothe undiluted water-in-water dispersion. This is, however,disadvantageous for the application of the water-in-water dispersions.

[0005] European application EP-A-0 630 909 describes a method formanufacturing water-in-water dispersions, according to which apolyvalent, anionic salt is added to the dispersed monomer solution tobe polymerised in quantities of at least 15% by weight for viscositycontrol. More salt is added to reduce the viscosity of thewater-in-water dispersions obtained. Again, the large quantity of saltadded means that the water-in-water dispersions cannot be used withoutdifficulty for every application.

[0006] Moreover, in the case of the water-in-water dispersions knownfrom the prior art, prolonged storage, especially under extremeconditions, such as temperatures of over 25° C. to 50° C., can result inchanges, i.e. impairments of the advantageous properties ofwater-in-water dispersions, which lead to longer drainage times, forexample.

[0007] Consequently, the object of the present invention was to providea method by which water-in-water polymer dispersions are obtained thatdisplay virtually unchanged service properties even after storage underextreme conditions, such as temperatures of over 25° C. to 50° C.

[0008] According to the invention, this is achieved by providing amethod for manufacturing a water-in-water polymer dispersion containinga water-soluble and/or water-swellable polymer A and a polymeric,water-soluble dispersant B, according to which the monomers, which aredispersed in an aqueous phase containing water-soluble dispersant B, aresubjected to radical polymerisation, possibly following the addition ofa water-soluble salt, and, after polymerisation, a water-soluble acid isadded to the water-in-water dispersion obtained in this way, which ischaracterised in that the acid is added in quantities of 0.1 to 0.5% byweight, the salt in quantities of up to a maximum of 3% by weight, eachreferred to the total dispersion, and the acid and the salt together areadded in quantities of a maximum of 5% by weight, referred to the totaldispersion.

[0009] The acid is preferably added in quantities of 0.2 to 3.5% byweight, particularly preferably in quantities of 0.3 to 2% by weight,referred to the total dispersion.

[0010] Insofar as a salt is used in manufacturing the water-in-waterpolymer dispersion, this salt is preferably added in quantities of up toa maximum of 2.0% by weight, particularly preferably in quantities of0.5 to 1.5% by weight, referred to the total dispersion. In thiscontext, the quantities of added water-soluble acid and possibly addedwater-soluble salt should preferably amount to a maximum of 3.5% byweight, referred to the total dispersion.

[0011] Water-soluble organic acids and/or inorganic acids can be used asthe acid added to the water-in-water polymer dispersions manufacturedaccording to the invention. Particularly suitable for use as organic,water-soluble acids are carboxylic acids, sulphonic acids, phosphonicacids, preferably aliphatic or aromatic monocarboxylic, dicarboxylic,polycarboxylic acids and/or hydroxycarboxylic acids, preferably aceticacid, propionic acid, citric acid, oxalic acid, succinic acid, malonicacid, adipic acid, fumaric acid, maleic acid, benzoic acid, mostparticularly preferably citric acid, adipic acid and/or benzoic acid.Suitable for use as inorganic acids are water-soluble mineral acids,preferably hydrochloric acid, sulphuric acid, nitric acid and/orphosphoric acid. Citric acid, adipic acid, benzoic acid, hydrochloricacid, sulphuric acid and/or phosphoric acid is used with particularpreference.

[0012] In order to implement the methods according to the invention, themonomers, preferably in the form of an aqueous monomer solution, arefinely dispersed in an aqueous phase containing at least one polymericdispersant B. These polymeric dispersants have a relatively low.molecular weight and preferably display an average molecular weightM_(w) of max. 2.0×10⁶, preferably 50,000 to 1.2×10⁶ g/mol, as measuredby the GPC method (gel permeation chromatography with 1.5% formic acidas eluent against pullulan standards).

[0013] These polymeric dispersants display at least one functional groupselected from the range of ether, carboxyl, sulpho, sulphate ester,amino, amido, imido, tert. amino and/or quaternary ammonium groups.

[0014] Cellulose derivatives, polyvinyl acetates, starch, starchderivatives, dextrans, polyvinylpyrrolidones, polyvinylpyridines,polyethylene imines, polyamines, polyvinylimidazoles,polyvinylsuccinimides, polyvinyl-2-methylsuccinimides,polyvinyl-1,3-oxazolidone-2, polyvinyl-2-methylimidazolines and/or theirrespective copolymers with maleic acid, maleic anhydride, fumaric acid,itaconic acid, itaconic anhydride, (meth)acrylic acid, salts of(meth)acrylic acid and/or (meth)acrylic amide compounds can be mentionedas examples of these.

[0015] Particularly preferably used as polymeric dispersants B arecationic polymers that are made up of at least 30% by weight, preferablyat least 50% by weight, particularly preferably 100% by weight, cationicmonomer units derived from cationic, ethyleneically unsaturatedmonomers, such as diallyldimethylammonium chloride,dialkylaminoalkyl(meth)acrylate or acrylamide with 1 to 3 C atoms in thealkyl or alkylene groups and protonated or quaternised into ammoniumsalts, preferably methyl chloride-quaternised ammonium salts ofdimethylaminoethyl(meth)acrylate, dimethylaminopropyl(meth)acrylate,dimethylaminopropyl(meth)acrylamide,dimethylaminohydroxypropyl(meth)acrylate. Polydiallyldimethylammoniumchloride is used with particular preference as the polymeric dispersantB in the method according to the invention.

[0016] In a preferred embodiment of the methods according to theinvention, the water-soluble, polymeric dispersant B is used togetherwith a water-soluble, polyfunctional alcohol and/or the product of itsreaction with fatty amines. Particularly suitable in this context arepolyalkylene glycols, preferably polyethylene glycols, polypropyleneglycols, block copolymers of propylene/ethylene oxide, with molecularweights of 50 to 50,000, preferably 1,500 to 30,000, low-molecularpolyfunctional alcohols, such as glycerin, ethylene glycol, propyleneglycol, pentaerythritol and/or sorbitol as polyfunctional water-solublealcohols, and/or the products of their reaction with fatty amines withC₆-C₂₂ in the alkyl or alkylene residue.

[0017] The aqueous phase in which the monomers are dispersed, preferablyin the form of an aqueous solution, must contain sufficientwater-soluble polymeric dispersant B and, if applicable, polyfunctionalalcohol and/or the reaction product mentioned for the polymer A formedduring polymerisation to remain dispersed and to prevent uncontrolledgrowth of the polymer particles and/or agglomeration of the polymerparticles formed. Polymeric dispersant B and the other dispersantcomponents possibly present are preferably added in quantities of 5 to50% by weight, preferably 10 to 20% by weight, referred to the totaldispersion.

[0018] If additional water-soluble dispersant components are used alongwith polymeric dispersant B, a weight ratio of polymeric dispersant B tothese components of 1:0.01 to 0.5, preferably 1:0.01 to 0.3, should bemaintained.

[0019] The monomers present in the aqueous phase containing polymericdispersant B in dispersed form, preferably in finely and homogeneouslydispersed form, comprise cationic and/or amphiphilic, ethyleneicallyunsaturated monomers, where their possibly present content ofwater-insoluble monomers is selected such as not to impair thewater-solubility or water-swellability of polymer A obtained afterpolymerisation.

[0020] Polymers A manufactured by the method according to the inventionare high-molecular, but nonetheless water-soluble or water-swellablepolymers with an average molecular weight of M_(w), as measured by theGPC method, of >1.0×10₆ g/mol, where the average molecular weight M_(w)of polymer A is always greater than that of polymeric dispersant B.

[0021] Compounds of the following general formula (I) can be used asnon-ionic monomers for manufacturing polymers A:

[0022] where

[0023] R₁ stands for hydrogen or a methyl residue, and

[0024] R² and R³ stand, independently of each other, for hydrogen, foran alkyl or hydroxyalkyl residue with 1 to 5 C atoms.

[0025] (Meth)acrylamide, N-methyl(meth)acrylamide,N-isopropyl(meth)acrylamide or N,N-substituted (meth)acrylamides, suchas N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide,N-methyl-N-ethyl(meth)acrylamide or N-hydroxyethyl(meth)acrylamide, ispreferably used, most particularly preferably acrylamide.

[0026] Compounds of the following general formula (II) are suitable ascationic monomers for manufacturing polymers A:

[0027] where

[0028] R¹ stands for hydrogen or a methyl residue,

[0029] Z¹ stands for O, NH or NR₄ with R₄ for an alkyl residue with 1 to4 C atoms, and

[0030] Y for one of the groups

[0031] and

[0032] where

[0033] Y₀ and Y₁ stand for an alkylene residue, possibly substitutedwith OH groups, with 2 to 6 C atoms,

[0034] Y₂, Y₃, Y₄, Y₅, Y₆, Y₇, independently of each other, stand for analkyl residue with 1 to 6 C atoms, and

[0035] Z⁻ stands for halogen, acetate, SO₄CH₃ ⁻.

[0036] Protonated or quaternised dialkylaminoalkyl(meth)acrylates ordialkylaminoalkyl(meth)acrylamides with C₁ to C₃ in the alkyl oralkylene groups are preferably suitable, particularly preferably themethyl chloride-quaternised ammonium salt ofdimethylaminoethyl(meth)acrylate, dimethylaminopropyl(meth)acrylate,dimethylaminoethyl(meth)acrylate, diethylaminoethyl(meth)acrylate,dimethylaminomethyl(meth)acrylate, dimethylaminoethyl(meth)acrylamideand/or dimethylaminopropyl(meth)acrylamide.

[0037] Compounds of the following general formula (III) or (IV) aresuitable as amphiphilic monomers:

[0038] where

[0039] Z₁ stands for O, NH or NR₄ with R₄ for alkyl with 1 to 4 carbonatoms,

[0040] R₁ stands for hydrogen or a methyl residue,

[0041] R₈ stands for alkylene with 1 to 6 carbon atoms,

[0042] R₅ and R₆ stand, independently of each other, for an alkylresidue with 1 to 6 carbon atoms,

[0043] R₇ stands for an alkyl, aryl and/or aralkyl residue with 8 to 32carbon atoms, and

[0044] Z⁻ stands for halogen, pseudo-halogen, SO₄CH₃ ⁻ or acetate or

[0045] where

[0046] Z₁ stands for O, NH or NR₄ with R₄ for alkyl with 1 to 4 carbonatoms,

[0047] R₁ stands for hydrogen or a methyl residue,

[0048] R₁₀ stands for hydrogen, an alkyl, aryl and/or aralkyl residuewith 8 to 32 carbon atoms,

[0049] R₉ stands for an alkylene residue with 2 to 6 carbon atoms, and

[0050] n stands for an integer between 1 and 50.

[0051] These are preferably conversion products of (meth)acrylic acidwith polyethylene glycols (10 to 40 ethylene oxide units) that have beenetherified with fatty alcohol, or the corresponding conversion productswith (meth)acrylamide.

[0052] For manufacturing polymer A, a monomer composition is preferablyselected which consists of 1 to 99% by weight, preferably 20 to 80% byweight, cationic monomers, referred in each case to the total quantityof monomer. Particularly preferably, polymer A is manufactured using amixture of non-ionic monomers, preferably acrylamide, and cationicmonomers of general formula II, preferably quaterniseddialkylaminoalkyl(meth)acrylates and/ordialkylaminoalkyl(meth)acrylamides. Most particularly preferably,dimethylaminoethyl(meth)acrylate quaternised with methyl chloride isused. In monomer mixtures of this kind, the content of cationic monomersis preferably at least 20%.

[0053] Referred to the total solution or to the resultant totaldispersion, the monomers are dispersed in quantities of 5 to 60% byweight, preferably 10 to 50% by weight, in the aqueous phase, whichcontains at least one dispersant B. High-molecular polymer A is formedfrom the monomers by polymerisation.

[0054] Polymeric dispersant B and polymer A are different, where thisdifference can be a result of physical parameters, such as differentmolecular weights and/or chemical structures, or of different monomercompositions.

[0055] In the method according to the invention, polymerisation ispreferably performed in the presence of a water-soluble salt. Ammonium,alkaline metal and/or alkaline-earth metal salts can be used as thewater-soluble salt, preferably ammonium, sodium, potassium, calciumand/or magnesium salts. Salts of this kind can be salts of an inorganicacid or an organic acid, preferably of an organic carboxylic acid,sulphonic acid or phosphonic acid, or of a mineral acid. Thewater-soluble salts are preferably salts of an aliphatic or aromaticmonocarboxylic, dicarboxylic or polycarboxylic acid, a hydoxycarboxylicacid, preferably acetic acid, propionic acid, citric acid, oxalic acid,succinic acid, malonic acid, adipic acid, fumaric acid, maleic acid orbenzoic acid or sulphuric acid, hydrochloric acid or phosphoric acid.Most particularly preferably, sodium chloride, ammonium sulphate and/orsodium sulphate are used as water-soluble salts.

[0056] The salt can be added to the system before polymerisation, duringpolymerisation or after polymerisation. Addition of the salt beforepolymerisation of the monomers is preferred.

[0057] Following polymerisation, a water-soluble acid is added to thewater-in-water polymer dispersion in quantities of 0.1 to 5% by weight,preferably in quantities of 0.2 to 3.5% by weight, particularlypreferably in quantities of 0.3 to 2.0% by weight, referred in each caseto the total dispersion. Addition is preferably performed whilestirring. Suitable water-soluble acids are organic acids and/orinorganic acids, preferably organic carboxylic acids, sulphonic acids,phosphonic acids or mineral acids.

[0058] Preferably suitable as organic acids are carboxylic acids, suchas aliphatic or aromatic monocarboxylic, dicarboxylic, polycarboxylicacids and/or hydroxycarboxylic acids, preferably acetic acid, propionicacid, citric acid, oxalic acid, succinic acid, malonic acid, adipicacid, fumaric acid, maleic acid, benzoic acid, particularly preferablycitric acid, adipic acid and/or benzoic acid, while hydrochloric acid,sulphuric acid and/or phosphoric acid are preferably suitable asinorganic acids. Citric acid, adipic acid and/or benzoic acid areparticularly preferred.

[0059] In order to implement the method according to the invention, thecontinuous aqueous phase is produced by dissolving or diluting polymericdispersant B, possibly a polyfunctional alcohol and/or a correspondingproduct of conversion with fatty amines, in water and dispersing themonomers or their aqueous solution by known dispersion methods,preferably by stirring.

[0060] The monomers of polymer A can be incorporated into the continuousaqueous phase either directly as such or preferably in the form of anaqueous monomer solution.

[0061] The monomer solution generally contains 5 to 60% by weight,preferably 10 to 50% by weight, monomers, referred to the totalsolution, while the remainder consists of water and any auxiliariescontained therein, such as chelating agents. Polymerisation is started,for example, by means of radical initiators referred to aspolymerisation initiators. The radical initiators used are preferablyazo compounds, such as 2,2-azobiisobutyronitrile,2,2-azobis(2-amidino-propane)dihydrochloride or, preferably, potassiumpersulphate, ammonium persulphate, hydrogen peroxide, possibly incombination with a reducing agent, such as an amine or sodium sulphite.Referred to the monomers to be polymerised, the quantity of initiator isgenerally in the region of 10⁻³ to 1% by weight, preferably 10⁻² to 0.1%by weight. The initiators can either be added completely at the start ofpolymerisation, or also only partly with subsequent addition of theremainder throughout the course of polymerisation. Similarly, themonomers or the monomer solution can be completely or partly dispersedin dispersant B at the start of polymerisation, in which case theremainder of the monomers or the monomer solution is added in meteredpartial quantities or as a continuous stream distributed over the entirecourse of polymerisation. Moreover, it is also possible to manufacturethe water-in-water dispersions in accordance with the method in EP-A-0664 302, the corresponding disclosure of which is herewith introduced asa reference. Essentially, this procedure involves the removal of waterbeing during polymerisation and, if necessary, the addition of polymericdispersant B.

[0062] The polymerisation temperature is generally 0 to 120° C.,preferably 50 to 90° C. Polymerisation is preferably performed in such away that the system is flushed with inert gas and polymerisation takesplace in an inert-gas atmosphere, e.g. in a nitrogen atmosphere. Thepolymerisation conversion or the end of polymerisation can easily beascertained by determining the residual monomer content. The methods fordoing this are known to a person skilled in the art.

[0063] Following polymerisation, it may be advantageous to cool thereaction mixture before the acid is added, preferably while stirring thedispersion.

[0064] The method according to the invention succeeds in producingwater-in-water dispersions within generally short manufacturing times.

[0065] The water-in-water polymer dispersions obtainable according tothe invention have the unexpected advantage that, not only afterproduction, i.e. before being stored for any length of time, andpossibly after dilution with water, they are excellent flocculants inthe sedimentation of solids, preferably in the conditioning of water andprocess water or the treatment of waste water or in the extraction ofraw materials, preferably of coal, aluminium or petroleum, auxiliariesin papermaking or demulsifiers in the separation of water mixturescontaining oil and/or grease, excellent thickeners, retention agents anddrainage aids in papermaking and/or additives for crop protectionproducts, possibly together with other biologically effectivesubstances, or anti-erosion agents. The water-in-water dispersionsobtainable according to the invention display virtually no change inthis excellent efficacy even after lengthy storage under extremeconditions, e.g. at elevated temperatures, i.e. temperatures of morethan 25° C. and up to a maximum of 50° C. This preservation of qualityof the dispersions obtainable according to the invention is a hithertounfulfilled demand of users in industry and indispensable if, amongother things, these dispersions are to be transported to, and used in,regions subject to extreme climatic conditions.

[0066] Methods

[0067] 1. Determination of the Solution Viscosity

[0068] To determine the solution viscosity of the water-in-waterdispersions manufactured according to the invention, a 5% by weightsolution in fully demineralised water is prepared, referred to thewater-in-water polymer dispersion. 340 g of the 5% solution are requiredfor the measurement. To this end, the necessary quantity of fullydemineralised water is placed in a 400 ml beaker. The water in thebeaker is then stirred with a finger agitator so vigorously that avortex forms that reaches down to the bottom of the beaker. The amountof water-in-water dispersion required to prepare the 5% solution isadded to the agitated water in the beaker as a single dose using adisposable syringe. The solution is then stirred for 1 hour at 300 rpm(±10 rpm). After standing for 10 minutes, the Brookfield viscosity isdetermined with the help of an RVT-DV II Brookfield viscometer using aNo. 2 spindle at speed 10.

[0069] 2. Determination of the Salt Viscosity

[0070] 289 g fully demineralised water are weighed into a 400 ml beaker.The water in the beaker is then stirred with a finger agitator sovigorously that a vortex forms that reaches down to the bottom of thebeaker. 17 g of the water-in-water dispersion prepared according to theinvention are added to the agitated water in the beaker as a single doseusing a disposable syringe. Once the water-in-water dispersion hasdissolved, 34 g sodium chloride (technical) are strewn in. The solutionis stirred for 60 minutes at 300±10 rpm and then left to stand foranother 10 minutes. The Brookfield viscosity is subsequently determinedwith the help of an RVT-DV II Brookfield viscometer using a No. 1spindle at speed 10.

[0071] 3. Determination of the Flocculation Value Using StammbergeSlurry

[0072] This method is used to determine the sedimentation time requiredby the flocculated solid during solid/liquid separation by sedimentationto sediment through a defined stretch of the liquid column. Forimplementation of the method, refer to the publication by J. Reuter in“Umwelt” January 1981, pages 25 to 27.

[0073] A dispersion of the following substances is first prepared forthe measurement:

[0074] The solid used is “Blauton HFF-Spezial”, approx. 37% Al₂O₃>95%under 2 μm (Tonwerke Braun Witterschlick/Bonn), which is dispersed inKrefeld tap water (or synthetic tap water of 25° German hardness).

[0075] To this end, 18 g Blauton are added to 1000 ml tap water.

[0076] The mixture is then dispersed with a mixer (10,000±100 rpm ) for20 seconds.

[0077] The resultant dispersion is poured into a standardised testcylinder (see FIG. 1) up to the top mark.

[0078] The test cylinder has two marks 40 mm apart, is made ofplexiglass and holds 250 ml up to the top mark. The numbers in FIG. 1are in millimetres.

[0079] Preparation of the water-in-water dispersion for determination ofthe flocculation value:

[0080] The water-in-water dispersions to be tested are diluted with tapwater to a polymer content of 0.01% by weight in accordance with theirpolymer content (polymer A and polymeric dispersant B).

[0081] In order to measure the flocculation value, the test cylinderfilled with the clay dispersion described above is placed under a fingeragitator.

[0082] While stirring (320 rpm), 2.5 ml aluminium sulphate solution (200g Al₂(SO₄)₃×18 H₂O/litre distilled water) are added, after which 5 ml ofthe 0.01% polymer solution described above are added within 15 secondsand the agitator is switched off after a further 5 seconds. This nowgives rise to flocculation (agglomeration) of the clay dispersion, whichsettles rapidly. Measurement of the time is started once the clay flocshave reached the upper (first) mark on the test cylinder. The time takento reach the lower (second) mark is referred to as the flocculationvalue in seconds.

[0083] The smaller the flocculation value, the more advantageous theeffect of the flocculant.

[0084] 4. Determination of Drainage Acceleration Using aSchopper-Riegler Beating and Freeness Tester

[0085] This test method is described by H. Becker and D. Zerler in the“Schriftenreihe der Papiermacherschule”, Vol. 15, first edition 1995,pp. 68 to 71.

[0086] According to this test method, the acceleration of drainageresulting from the addition of water-in-water dispersions to definedpulp suspensions is determined with the help of a Schopper-Rieglerbeating and freeness tester (Haage).

[0087] To this end, water-in-water dispersions are adjusted to a polymercontent (polymer A and polymeric dispersant B) of 0.01% by weight, usingfully demineralised water in each case. The drainage apparatus used isthe above-mentioned Schopper-Riegler apparatus, which comprises a 2000ml metal cup with a wire on the underside which is sealed off with acone during filling.

[0088] The acceleration of drainage is determined on a 1% by weight pulpsuspension made of standard recovered paper.

[0089] To this end, 3 g oven-dry recovered paper fibres are adjustedwith tap water to 300 g of a 1% by weight pulp suspension in theSchopper-Riegler freeness cup. The drainage accelerating agent describedabove, consisting of a water-in-water dispersion, is adjusted to a 0.01%by weight solution. The drainage tests are performed with 3 polymerconcentrations, where 3 ml, 6 ml and 9 ml of the 0.01% drainage agentare each diluted with 200 ml tap water and this solution is added to thepaper fibre suspension in the Schopper-Riegler freeness cup and made. upto 1000 ml with tap water in each case. The contents of the cup are thentransferred to the filling chamber of the Schopper-Riegler apparatus,which is closed at the bottom, and the sealing cone is immediatelyunlocked. The time is measured that is required to filter off 700 ml ofthe 1000 ml paper fibre suspension after opening the sealing cone. Tothis end, the filtrate is collected and the time taken to reach 700 mlrecorded. This time is referred to as the drainage time.

EXAMPLES

[0090] In the following examples, the solution viscosity or saltviscosity, the flocculation value and the drainage effect weredetermined in accordance with the methods described above. The term“solution” is always taken to mean an aqueous solution.

Example 1

[0091] 231.0 g acrylamide solution (50%), 231.1 g fully demineralisedwater, 43.2 g dimethylaminoethylacrylate quaternised with methylchloride (80%), 9.5 g technical ammonium sulphate, 0.2 g of the sodiumsalt of diethylenetriamine pentaacetic acid (40%), 400 gpolydiallyldimethylammonium chloride (40%), 14.25 g polyethylene glycolwith a molecular weight of 9,000 to 12,000 and 5 g2,2-azobis(2-amidinopropane)dihydrochloride are put into a 2 l flaskfitted with an agitator, a nitrogen supply line and a connection to avacuum pump and dispersed homogeneously by stirring. The flask isdeaerated for approx. 10 minutes by connecting it to a vacuum pump andthe mixture is then blown out with nitrogen for approx. 15 minutes inorder to remove the remaining oxygen. While stirring at 100 to 150 rpm,the mixture is heated to 35° C. in order to polymerise the monomers.Once a maximum temperature of 75° C. has been reached, the mixture isbriefly re-stirred for 15 minutes. Subsequently, 10 g citric acid infine powder form are strewn in and mixed with the dispersion bystirring. After 20 minutes of constant stirring, the water-in-waterdispersion obtained is cooled to 20° C.

[0092] The solution viscosity of the water-in-water dispersion wasdetermined as being 60 mPa·s, as described above. The salt viscosity was36 mPa·s, again as described above.

Comparative Example 1

[0093] Example 1 was repeated, with the difference that citric acid wasnot added at any time.

[0094] The 5% solution viscosity of the water-in-water dispersion thusobtained was determined, as described above, as being 52 mPa·s and thesalt viscosity as being 32 mPa·s.

Example 2

[0095] 231.0 g acrylamide solution (50%), 231.1 g fully demineralisedwater, 43.2 g dimethylaminoethylacrylate quaternised with methylchloride (80%), 9.5 g technical ammonium sulphate, 0.2 g of the sodiumsalt of diethylenetriamine pentaacetic acid (40%), 400 gpolytrimethammoniumpropylacrylamide chloride (40%), 14.25 g polyethyleneglycol with a molecular weight of 9,000 to 12,000 and 4 g2,2-azobis(2-amidinopropane)dihydrochloride are put into a 2 l flaskfitted with an agitator, a nitrogen supply line and a connection to avacuum pump and dispersed by stirring. The flask is deaerated forapprox. 10 minutes by connecting to a vacuum pump and the mixture isthen blown out with nitrogen for approx. 15 minutes in order to removethe remaining oxygen. While stirring at 100 to 150 rpm, the mixture isheated to 35° C. in order to polymerise the monomers. Once a maximumtemperature of 76° C. has been reached, the mixture is brieflyre-stirred for 15 minutes. Subsequently, 10 g citric acid in fine powderform are strewn in and mixed with the dispersion by stirring. After 35minutes of constant stirring, the water-in-water dispersion obtained iscooled to 20° C.

[0096] The solution viscosity of the water-in-water dispersion wasdetermined as being 300 mPa·s, as described above. The salt viscositywas 150 mPa·s, again as described above.

Comparative Example 2

[0097] Example 2 was repeated, except that citric acid was not added atany time.

[0098] The 5% solution viscosity of the water-in-water dispersion thusobtained was determined, as described above, as being 280 mPa·s and thesalt viscosity, as described above, as being 135 mPa·s.

Example 3

[0099] 163.2 g fully demineralised water, 144.75 g 80% by weighttrimethylammonium ethylacrylate chloride, 231.0 g 50% by weightacrylamide solution, 420.0 g 40% by weight polydiallyldimethylammoniumchloride with a viscosity of the aqueous solution in the range of 200 to400 mPas, 14.0 g polyethylene glycol with a molecular weight in therange of 9,000 to 12,000, 12.2 g technical ammonium sulphate, 0.26 g 40%by weight diethylenetriamine valeric acid sodium salt and 1.54 g2,2-azobis(2-amidinopropane)dihydrochloride are put into a 2 l flaskfitted with an agitator, a nitrogen supply line and a connection to avacuum pump.

[0100] The pH value of the solution is 5.0. The solution is freed ofoxygen and polymerised in accordance with the procedure specified inExample 1. After a maximum temperature of 82° C. has been reached, 12.85g fine citric acid powder are mixed into the water-in-water dispersionby stirring, as described in Example 1, and the dispersion is thencooled to 20° C. while stirring constantly. The polymer content of thedispersion is 39.9% by weight.

[0101] The dispersion has a solution viscosity of 730 mPas and a saltviscosity of 210 mPas. A salt viscosity of 214 mPas is determined afterstoring the dispersion for a period of 60 days at a temperature of 40°C.

Comparative Example 3

[0102] Example 3 was repeated, but without adding citric acid at anytime.

[0103] The dispersion thus obtained has a solution viscosity of 700 mPasand a salt viscosity of 190 mPas. A salt viscosity of 136 mPas isdetermined after storage of the dispersion for a period of 60 days at atemperature of 40° C., this corresponding to a decrease of 28.4%referred to the value after preparation of the dispersion.

Example 4

[0104] 272.6 g fully demineralised water, 66.9 g 80% by weighttrimethylammonium ethylacrylate chloride, 321.0 g 50% by weightacrylamide solution, 310.0 g 40% by weightpolytrimethylammoniumpropylacrylamide chloride with a viscosity of theaqueous solution in the range of 150 to 300 mPas, 20.0 g technicalammonium sulphate, 2.0 g 5% by weight diethylenetriamine valeric acidsodium salt and 0.5 g 2,2-azobis(2-amidinopropane)dihydrochloride areput into a 2 l flask fitted with an agitator, a nitrogen supply line anda connection to a vacuum pump.

[0105] The solution is freed of oxygen, heated to 40° C. and polymerisedin accordance with the procedure specified in Example 1. After a maximumtemperature of 86° C. has been reached, 5.0 g fine citric acid powderare mixed into the water-in-water polymer dispersion by stirring and thedispersion is then cooled to 20° C. while stirring constantly. Thepolymer content of the dispersion is 33.8% by weight.

[0106] The dispersion has a solution viscosity of 564 mPas and a saltviscosity of 248 mPas. The solution viscosity is 308 mPas after storageof the dispersion for a period of 55 days at a temperature of 50° C.,this corresponding to a decrease of 45.4% referred to the value afterpreparation of the dispersion.

Example 5

[0107] A water-in-water polymer dispersion is prepared as in Example 4,except that the monomer solution contains 267.6 g water and 10.0 g finecitric acid powder are added after polymerisation.

[0108] The dispersion has a solution viscosity of 548 mPas and a saltviscosity of 227 mPas. The solution viscosity is 336 mPas after storageof the dispersion for a period of 55 days at a temperature of 50° C.,this corresponding to a decrease of 38.7% referred to the value afterpreparation of the dispersion.

Example 6

[0109] A water-in-water polymer dispersion is prepared as in Example 4,except that the monomer solution contains 257.6 g water and 20.0 g finecitric acid powder are added after polymerisation.

[0110] The dispersion has a solution viscosity of 572 mPas and a saltviscosity of 226 mPas. The solution viscosity is 416 mPas after storageof the dispersion for a period of 55 days at a temperature of 50° C.,this corresponding to a decrease of 27.3% referred to the value afterpreparation of the dispersion.

Comparative Example 4

[0111] Example 4 was repeated, but without adding citric acid at anytime.

[0112] The dispersion has a solution viscosity of 500 mPas and a saltviscosity of 208 mPas. The solution viscosity is 5 mPas after storage ofthe dispersion for a period of 55 days at a temperature of 50° C., thiscorresponding to a decrease of 99% referred to the value afterpreparation of the dispersion.

Example 7

[0113] A monomer solution is prepared, as described in Example 4. 2.0 g30% hydrochloric acid are additionally mixed into the solution, which ispolymerised in accordance with the procedure specified in Example 1. 5.0g adipic acid are then mixed into the water-in-water polymer dispersion,which is then cooled in the manner described.

[0114] The dispersion has a solution viscosity of 708 mPas and a saltviscosity of 298 mPas.

[0115] The solution viscosity determined is 464 mPas after storage ofthe dispersion for a period of 45 days at a temperature of 50° C., thiscorresponding to a decrease of 34.5% referred to the value afterpreparation of the dispersion.

Example 8

[0116] A monomer solution is prepared, as described in Example 4. 2.0 g30% hydrochloric acid are additionally mixed into the solution, which ispolymerised in accordance with the procedure specified in Example 1. 5.0g benzoic acid are then mixed into the water-in-water polymerdispersion, which is then cooled in the manner described.

[0117] The dispersion has a solution viscosity of 768 mPas and a saltviscosity of 319 mPas.

[0118] The solution viscosity determined is 532 mPas after storage ofthe dispersion for a period of 45 days at a temperature of 50° C., thiscorresponding to a decrease of 30.7% referred to the value afterpreparation of the dispersion.

Example 9

[0119] A monomer solution is prepared, as described in Example 4. 2.0 g30% hydrochloric acid are additionally mixed into the solution, which ispolymerised in accordance with the procedure specified in Example 1. 0.5g 50% sulphuric acid are then mixed into the water-in-water polymerdispersion, which is then cooled in the manner described.

[0120] The dispersion has a solution viscosity of 716 mPas and a saltviscosity of 290 mPas.

[0121] The solution viscosity determined is 460 mPas after storage ofthe dispersion for a period of 45 days at a temperature of 50° C., thiscorresponding to a decrease of 35.8% referred to the value afterpreparation of the dispersion.

Example 10

[0122] A monomer solution is prepared, as described in Example 4. 2.0 g30% hydrochloric acid are additionally mixed into the solution, which ispolymerised in accordance with the procedure specified in Example 1. 2.5g acetic acid are then mixed into the water-in-water polymer dispersion,which is then cooled in the manner described.

[0123] The dispersion has a solution viscosity of 940 mPas and a saltviscosity of 395 mPas.

[0124] The solution viscosity determined is 656 mPas after storage ofthe dispersion for a period of 45 days at a temperature of 50° C., thiscorresponding to a decrease of 30.2% referred to the value afterpreparation of the dispersion.

Example 11

[0125] A monomer solution is prepared, as described in Example 4. 2.0 g30% hydrochloric acid are additionally mixed into the solution, which ispolymerised in accordance with the procedure specified in Example 1. 5.0g citric acid are then mixed into the water-in-water polymer dispersion,which is then cooled in the manner described.

[0126] The dispersion has a solution viscosity of 780 mPas and a saltviscosity of 341 mPas.

[0127] The solution viscosity determined is 504 mPas after storage ofthe dispersion for a period of 45 days at a temperature of 50° C., thiscorresponding to a decrease of 35.4% referred to the value afterpreparation of the dispersion.

Comparative Example 5

[0128] A monomer solution is prepared, as described in Example 4. 2.0 g30% hydrochloric acid are additionally mixed into the solution, which ispolymerised and cooled in accordance with the procedure specified inExample 1.

[0129] The dispersion has a solution viscosity of 680 mPas and a saltviscosity of 287 mPas. The solution viscosity determined is 368 mPasafter storage of the dispersion for a period of 45 days at a temperatureof 50° C., this corresponding to a decrease of 45.9% referred to thevalue after preparation of the dispersion.

Example 12

[0130] The procedure described in Example 11 is used, except that themonomer solution now contains 20.0 g sodium chloride instead of 20.0 gtechnical ammonium sulphate. The dispersion has a solution viscosity of752 mPas and a salt viscosity of 302 mPas.

[0131] The solution viscosity determined is 568 mPas after storage ofthe dispersion for a period of 45 days at a temperature of 50° C., thiscorresponding to a decrease of 24.5% referred to the value afterpreparation of the dispersion.

Example 13

[0132] The procedure described in Example 11 is used, except that themonomer solution now contains 20.0 g sodium sulphate 10 H₂0 instead of20.0 g technical ammonium sulphate. The dispersion has a solutionviscosity of 976 mPas and a salt viscosity of 406 mPas.

[0133] The solution viscosity determined is 672 mPas after storage ofthe dispersion for a period of 45 days at a temperature of 50° C., thiscorresponding to a decrease of 31.1% referred to the value afterpreparation of the dispersion.

Example 14

[0134] 305.5 g fully demineralised water, 135.5 g 80% by weighttrimethylammonium ethylacrylate chloride, 195.2 g 50% by weightacrylamide solution, 300.0 g 40% by weightpolytrimethylammoniumpropylacrylamide chloride with a viscosity of theaqueous solution in the range of 150 to 300 mPas, 20.5 g polyethyleneglycol with a molecular weight in the range of 9,000 to 12,000, 5.0 gtechnical ammonium sulphate and 2.0 g 5% by weight diethylenetriaminevaleric acid sodium salt are put into a 2 l flask fitted with anagitator, a nitrogen supply line and a connection to a vacuum pump.

[0135] The pH of the solution is 5.0.

[0136] In accordance with the procedure specified in Example 1, thesolution is freed of oxygen, heated to 40° C. and polymerised by adding1 ml of a 5% by weight aqueous solution of sodium disulphate and 5 ml0.01% by weight tertiary butyl hydroperoxide. If necessary, furthersmall quantities of tertiary butyl hydroperoxide are subsequently added.After a maximum temperature of 56° C. has been reached, 5.0 g finecitric acid powder are mixed into the water-in-water polymer dispersionby stirring and the dispersion is then cooled to 20° C. while stirringconstantly. The polymer content of the dispersion is 33.5% by weight.

[0137] The dispersion has a solution viscosity of 912 mPas and a saltviscosity of 151 mPas. The solution viscosity is 732 mPas after storageof the dispersion for a period of 42 days at a temperature of 50° C.,this corresponding to a decrease of 19.7% referred to the value afterpreparation of the dispersion.

Example 15

[0138] A water-in-water polymer dispersion is prepared as in Example 14,except that the monomer solution contains 300.5 g water and 10.0 g finecitric acid powder are added after polymerisation.

[0139] The dispersion has a solution viscosity of 1380 mPas and a saltviscosity of 225 mPas. The solution viscosity is 1410 mPas after storingthe dispersion for a period of 42 days at a temperature of 50° C.

Comparative Example 6

[0140] Example 15 is repeated, the difference being that no citric acidis added after polymerisation.

[0141] The dispersion has a solution viscosity of 1240 mPas and a saltviscosity of 214 mPas. The solution viscosity is 256 mPas after storageof the dispersion for a period of 42 days at a temperature of 50° C.,this corresponding to a decrease of 79.4% referred to the value afterpreparation of the dispersion.

Application Examples I-VIII

[0142] The respective flocculation values of the water-in-waterdispersions obtained in accordance with Examples 1 and 2 and Comparativeexamples 1 and 2 were determined by the method described above, bothimmediately after preparation and after storage in closed containers for20 days at 50° C.

[0143] The corresponding flocculation values in seconds are stated inTable I, below. TABLE I Flocculation Application value exampleWater-in-water dispersion according to (s) I Example 1, day ofpreparation 12.8 II Example 1, after storage for 20 days at 12.9 50° C.Ill Comparative example 1, day of preparation 12.6 IV Comparativeexample 1, after storage for 20 34.6 days at 50° C. V Example 2, day ofpreparation 6.8 VI Example 2, after storage for 20 days at 7.2 50° C.VII Comparative example 2, day of preparation 7.0 VIII Comparativeexample 2, after storage for 20 23.9 days at 50° C.

[0144] The water-in-water dispersions obtained in accordance withExamples 1 and 2 and Comparative examples 1 and 2 were used as drainageaids, both after preparation and after storage in a sealed container for20 days at 50° C. Their effect was determined in accordance with theabove-mentioned Schopper-Riegler method. The corresponding values arestated in Table II, below. TABLE II Application Drainage exampleWater-in-water dispersion according to time (s) IX A Example 1, day ofpreparation 98 IX B Example 1, day of preparation 79 IX C Example 1, dayof preparation 61 X A Example 1, after storage for 20 days at 50° C. 99X B Example 1, after storage for 20 days at 50° C. 77 X C Example 1,after storage for 20 days at 50° C. 60 XI A Comparative example 1, dayof preparation 96 XI B Comparative example 1, day of preparation 80 XI CComparative example 1, day of preparation 61 XII A Comparative example1, after storage for 20 122 days at 50° C. XII B Comparative example 1,after storage for 20 118 days at 50° C. XII C Comparative example 1,after storage for 20 90 days at 50° C. XIII A Example 2, day ofpreparation 82 XIII B Example 2, day of preparation 60 XIII C Example 2,day of preparation 50 XIV A Example 2, after storage for 20 days at 50°C. 84 XIV B Example 2, after storage for 20 days at 50° C. 60 XIV CExample 2, after storage for 20 days at 50° C. 50 XV A Comparativeexample 2, day of preparation 83 XV B Comparative example 2, day ofpreparation 61 XV C Comparative example 2, day of preparation 51 XVI AComparative example 2, after storage for 20 101 days at 50° C. XVI BComparative example 2, after storage for 20 82 days at 50° C. XVI CComparative example 2, after storage for 20 66 days at 50° C.

[0145] Application of the water-in-water dispersions obtained inaccordance with Examples 3 to 15 and Comparative examples 3 to 6.

[0146] As indicated in Table III, the flocculation value (FV) of each ofthese water-in-water dispersions was determined by the method describedabove, both immediately after preparation and after storage for 20 daysin a sealed container at 25° C. (RT) or 50° C. The drainage effect wasalso determined by the method described above after the specifiedstorage. TABLE III Storage for 20 days Storage after . . . days SaltSolution FV Salt Solution FV Pulp Drainage* Salt Ex. viscosity viscosityStb II pT value Temp. viscosity viscosity Stb II 0.05% 0.1% 0.2% Temp.viscosity No. [mPa*s] [mPa*s] [sec] 5% in FDW [° C.] [mPa*s] [mPa*s][sec.] [Sec.] [sec.] [sec.] [° C.] Days [mpa*s]  3 210 730 4.8 3.0 RT232 1040 6.6 69 46 30 RT appr. 60 225 40° C. 222 1072 6.5 70 47 30 40°C. appr. 60 214 C3 190 700 5.7 45 RT 196 704 7.4 71.5 49 32 RT appr. 60192 40° C. 155 532 7.4 73 49.5 33.5 40° C. appr. 60 136  4 248 564 7.337 RT 204 520 7.6 71 46 27.5 RT appr. 60 220 50° C. 199 432 7.5 71 50 2950° C. appr. 60 184 C4 208 500 8.2 4.9 RT 187 436 10.2 62.5 38 28 RTappr. 55 174 50° C. 77 76 19 75 52 38 50° C. appr. 55 1  5 227 548 7 3.3RT 214 520 68 74 46 30 RT appr. 55 217 50° C. 206 452 8.2 75 49.5 31.550° C. appr. 55 200 C5 287 680 6.3 3.6 RT 270 636 7 66 43.5 26 RT appr.55 257 50° C. 237 492 7.4 70 45 28 50° C. appr. 55 228  6 226 572 6.73.1 RT 226 548 7 70 49 29 RT appr. 55 225 50° C. 228 488 7 72 52 31 50°C. appr. 55 214 C6 214 1240 8.5 4.2 RT 198 1150 9.4 75 51 29 RT appr. 42170 50° C. 105 495 16.4 86 59 35 50° C. appr. 42 62  7 298 708 5.8 3.6RT 323 732 6.6 71 44 23 RT appr. 50 287 50° C. 285 600 6.8 75 47 24 50°C. appr. 50 245  8 319 768 5.8 3.7 RT 332 784 6 70 41 24.5 RT appr. 45315 50° C. 301 644 6.3 83 50 29.5 50° C. appr. 45 276  9 290 716 6.2 3.8RT 298 708 6.3 79.5 44 27 RT appr. 45 302 50° C. 260 520 6.6 86 48 28.550° C. appr. 45 252 10 395 940 5.4 3.7 RT 402 932 5 82 46 26.5 RT appr.45 408 50° C. 368 776 5.4 98 56 31 50° C. appr. 45 352 11 341 780 5.83.3 RT 298 740 6.4 65 43 25.5 RT appr. 60 318 50° C. 308 676 6 67 44 2550° C. appr. 60 280 12 302 752 6.3 3.4 RT 302 728 6.5 70 44 24 RT appr.50 308 50° C. 296 680 6.5 73 45 24 50° C. appr. 50 268 13 406 976 5.23.4 RT 426 996 4.8 69 42 21 RT appr. 50 404 50° C. 390 864 5 70 45 2150° C. appr. 50 342 14 151 912 12.3 3.4 RT 145 910 12.5 79 56 30 RTappr. 42 134 50° C. 135 854 13 81 56 31 50° C. appr. 42 123 15 225 13808.1 3.3 RT 200 1260 9.9 73 48.5 26 RT appr. 42 202 50° C. 200 1560 10.174 49 28 50° C. appr. 42 198 Solution FV pH value Viscosity Ex.viscosity Stb II 5% in drop** No. [mPa*s] [sec.] FDW [%]  3 854 6.4 3.11.9 808 6.5 3.1 C3 688 74 4.4 456 8 4.4 −28.4  4 536 76 3.6 308 8.4 3.8−45.4 C4 360 12.4 4.8 5 >60 4.6 −99  5 520 7.2 3.2 336 7.9 3.5 −38.7 C5640 6.7 3.5 368 7 3.8 −45.9  6 552 7 3.1 416 7.2 3.3 −27.3 C6 1110 12.24.3 256 22 4.2 −79.4  7 696 6.5 3.7 464 6.7 3.6 −34.5  8 768 6.2 3.6 5326.4 3.6 −30.7  9 720 6.2 3.5 460 6.6 3.8 −35.8 10 928 5.1 3.5 656 5.43.7 −30.2 11 764 6 3.3 504 6.4 3.6 −35.4 12 772 6.4 3.4 568 6.6 3.4−24.5 13 968 5 3.4 672 5.2 3.5 −31.1 14 944 14.8 3.4 732 16.8 3.6 −19.715 1240 10.1 3.3 1410 13.6 3.3 26.1

1. Method for manufacturing a water-in-water polymer dispersioncontaining polymer A and at least one polymeric dispersant B, accordingto which monomers, which are dispersed in an aqueous phase containingwater-soluble dispersant B, are subjected to radical polymerisation,possibly following the addition of a water-soluble salt, and, afterpolymerisation, a water-soluble acid is added to the water-solubleand/or water-swellable polymer A obtained in this way, characterised inthat the acid is added in quantities of 0.1 to 0.5% by weight and thesalt in quantities of up to a maximum of 3% by weight, each referred tothe total dispersion, where the total quantity of salt and acid amountsto a maximum of 5% by weight, referred to the total dispersion. 2.Method as per claim 1, characterised in that the acid is added inquantities of 0.2 to 3.5% by weight, preferably 0.3 to 2.0% by weight,referred to the total dispersion.
 3. Method as per claim 1 or 2,characterised in that the salt is added in quantities of up to a maximumof 2.0% by weight, preferably 0.5 to 1.5% by weight, referred to thetotal dispersion.
 4. Method as per claims 1 to 3, characterised in thatthe acid and the salt are added in a total quantity of a maximum of 3.5%by weight, referred to the total dispersion.
 5. Method as per claims 1to 4, characterised in that the water-soluble acid used is an organicacid and/or an inorganic acid, preferably an organic carboxylic acid,sulphonic acid, phosphonic acid and/or mineral acid.
 6. Method as perclaim 5, characterised in that the carboxylic acid used is an aliphaticor aromatic monocarboxylic, dicarboxylic, polycarboxylic acid and/or ahydroxycarboxylic acid, preferably acetic acid, propionic acid, citricacid, oxalic acid, succinic acid, malonic acid, adipic acid, fumaricacid, maleic acid, benzoic acid, particularly preferably citric acid,adipic acid and/or benzoic acid.
 7. Method as per claim 5, characterisedin that the inorganic acid used is hydrochloric acid, sulphuric acid,nitric acid and/or phosphoric acid.
 8. Method as per claims 1 to 7,characterised in that the water-soluble salt used is an ammonium,alkaline metal and/or alkaline-earth metal salt.
 9. Method as per claim8, characterised in that the inorganic salt used is an ammonium, sodium,potassium, calcium and/or magnesium salt.
 10. Method as per claim 8 or9, characterised in that the salt is a salt of an inorganic acid or anorganic acid, preferably of an organic carboxylic acid, sulphonic acid,phosphonic acid or of a mineral acid.
 11. Method as per claim 10,characterised in that the water-soluble salt is a salt of an aliphaticor aromatic monocarboxylic, dicarboxylic or polycarboxylic acid, ahydoxycarboxylic acid, preferably acetic acid, propionic acid, citricacid, oxalic acid, succinic acid, malonic acid, adipic acid, fumaricacid, maleic acid, benzoic acid, sulphuric acid, hydrochloric acid orphosphoric acid.
 12. Method as per claim 11, characterised in that thewater-soluble salt used is sodium chloride, ammonium sulphate and/orsodium sulphate.
 13. Method as per claims 1 to 12, characterised in thatthe dispersant B used is a water-soluble polymer with a maximum M_(w) of2.0×10⁶, preferably 50,000 to 1.2×10⁶ g/mol, possibly mixed with apolyfunctional alcohol and/or a corresponding product of conversion witha fatty amine.
 14. Method as per claim 13, characterised in thatpolymeric dispersant B contains at least one functional group selectedfrom ether, carboxyl, sulpho, sulphate ester, amino, amido, imido,tertiary amino and/or quaternary ammonium groups.
 15. Method as perclaim 14, characterised in that polymeric dispersant B is a cellulosederivative, polyvinyl acetate, starch, starch derivative, dextran,polyvinylpyrrolidone, polyvinylpyridine, polyethylene imine, polyamine,polyvinylimidazole, polyvinyl succinimide,polyvinyl-2-methylsuccinimide, polyvinyl-1,3-oxazolidone-2,polyvinyl-2-methylimidazoline and/or their respective copolymer withmaleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconicanhydride, (meth)acrylic acid, salts of (meth)acrylic acid and/or a(meth)acrylic acid amide compound.
 16. Method as per claims 13 to 15,characterised in that dispersant B is a cationic polymer consisting ofat least 30% by weight, preferably at least 50% by weight, particularlypreferably 100% by weight, cationic monomer.
 17. Method as per claim 16,characterised in that the cationic monomer is a diallyl dimethylammoniumchloride, a dialkylaminoalkyl(meth)acrylate ordialkylaminoalkyl(meth)acrylamide with C₁-C₃ in the alkyl or alkylenegroups and protonated or quaternised as an ammonium salt, preferably themethyl chloride-quaternised ammonium salt ofdimethylaminoethyl(meth)acrylate, dimethylaminopropyl(meth)acrylate ordimethylaminopropyl(meth)acrylamide, particularly preferably diallyldimethylammonium chloride.
 18. Method as per claims 13 to 17,characterised in that the polyfunctional alcohol used is a polyalkyleneglycol, preferably polyethylene glycol, a block polymer ofpropylene/ethylene oxide with a molecular weight of 1,500 to 50,000,glycerin, ethylene glycol, propylene glycol, pentaerythritol and/orsorbitol.
 19. Method as per claims 1 to 18, characterised in thatpolymeric dispersant B and the polyfunctional alcohol possibly presentare added in quantities of 5 to 50% by weight, preferably 10 to 20% byweight, referred to the total dispersion.
 20. Method as per claims 13 to19, characterised in that the weight ratio of polymeric dispersant B tothe polyfunctional alcohol is 1:0.01 to 0.5, preferably 1:0.01 to 0.3.21. Method as per claims 1 to 20, characterised in that polymer A has anM_(w) of >1.0×10⁶ g/mol.
 22. Method as per claims 1 to 21, characterisedin that polymer A is made up of non-ionic and/or cationic and/oramphiphilic, ethyleneically unsaturated, preferably water-solublemonomers, where the content of water-insoluble monomers possibly presentis selected so as not to impair the water-solubility orwater-swellability of polymer A.
 23. Method as per claim 22,characterised in that the non-ionic monomers used are compounds ofgeneral formula (I)

where R¹ stands for hydrogen or a methyl residue, and R² and R³ stand,independently of each other, for hydrogen, for an alkyl or hydroxyalkylresidue with 1 to 5 C atoms, the cationic monomers used are compounds ofgeneral formula (II)

where R¹ stands for hydrogen or a methyl residue, Z₁ stands for O, NH orNR₄ with R₄ for an alkyl residue with 1 to 4 C atoms, and Y for one ofthe groups where

Y₀ and Y₁ stand for an alkylene residue, possibly substituted withhydroxy groups, with 2 to 6 C atoms, Y₂, Y₃, Y₄, Y₅, Y₆, Y₇,independently of each other, stand for an alkyl residue with 1 to 6 Catoms, and Z⁻ stands for halogen, acetate, SO₄CH₃ ⁻, and the amphiphilicmonomers are compounds of general formula (III) or (IV)

where Z₁ stands for O, NH, NR₄ with R₄ for an alkyl residue with 1 to 4carbon atoms, R₁ stands for hydrogen or a methyl residue, R₈ stands foran alkylene residue with 1 to 6 carbon atoms, R₅ and R₆ stand,independently of each other, for an alkyl residue with 1 to 6 carbonatoms, R₇ stands for an alkyl, aryl and/or aralkyl residue with 8 to 32carbon atoms, and Z⁻ stands for halogen, pseudo-halogen, SO₄CH₃ ⁻ oracetate, or

where Z₁ stands for O, NH, NR₄ with R₄ for an alkyl residue with 1 to 4carbon atoms, R₁ stands for hydrogen or a methyl residue, R₁₀ stands forhydrogen, an alkyl, aryl and/or aralkyl residue with 8 to 32 carbonatoms, R₉ stands for an alkylene residue with 2 to 6 carbon atoms, and nstands for an integer between 1 and
 50. 24. Method as per claim 22 or23, characterised in that polymer A is made up of 1 to 99% by weight,preferably 20 to 80% by weight, cationic monomers
 25. Method as perclaims 1 to 24, characterised in that polymer A is present in quantitiesof 5 to 60% by weight, preferably 10 to 50% by weight, referred to thetotal dispersion.
 26. Method as per claims 1 to 25, characterised inthat, for radical polymerisation, the initiator system is addedcontinuously during the entire course of polymerisation. 27.Water-in-water polymer dispersion obtainable by one or more of claims 1to
 26. 28. Use of the water-in-water polymer dispersion as per claim 27as a flocculant in the sedimentation of solids, preferably in theconditioning of water and process water or in waste water treatment, inraw materials extraction, preferably coal, aluminium or petroleum, as anauxiliary in papermaking or as a demulsifier in the separation of watermixtures containing oil and/or fat.
 29. Use of the water-in-waterpolymer dispersion as per claim 27 as a thickener.
 30. Use of thewater-in-water polymer dispersion as per claim 27 as a retention agentand drainage aid in papermaking.
 31. Use of the water-in-water polymerdispersion as per claim 27 as an additive for a crop protection agent,possibly together with other biologically effective substances.
 32. Useof the water-in-water polymer dispersion as per claim 27 as an additivefor an anti-erosion agent.